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Switch-Barrel Magic

T/C’s New Rifle Redefines Versatility.

If you thought the science around rifles with interchangeable calibers had been settled, you’re in for a great surprise. Most such rifles have European origins and are normally quite expensive. Thompson/Center’s new Dimension Rifle Platform is not only inexpensive at $599 retail for a complete rifle, it is a modular system allowing an owner to inexpensively acquire a new rifle in any of its 10 calibers and put it together in approximately 5 minutes. The caliber kits start at $199 retail for barrel and magazine group, and $99 if another bolt is needed due to a change in case head size.

The incredible versatility of the system offers calibers in four families called “A,” “B,” “C” and “D” based on case head size or cartridge length. The “A” family handles cartridges based on the .223 head size, “B” handles .308 Winchester-length, “C” .30-06-length cartridges and “D” the belted mags in the .300 Winchester Magnum length. By breaking down the calibers in this fashion and providing magazine groups for each family, the bolt only travels as far as needed in the receiver to feed and eject the cartridges in its family. The annoying problem of bolt overtravel during cycling of the small .223 in an action long enough for the .300 Win Mag is eliminated.

The rifle is a lightweight 6-1/2 pounds, slightly lighter in .223 and the initial offerings are hunting rifles. The weight reduction is chiefly accomplished by making the receiver out of aluminum, which also moves the balance point forward, giving the rifle superb handling characteristics. Since the steel bolt’s locking lugs engage recesses CNC machined into the barrel, all pressure containment is confined to the steel parts. The aluminum receiver only houses the bolt stop and trigger, which has a user-adjustable range from 3-1/2 pounds to 5 pounds. On the four pre-production samples we fired, all broke crisply and cleanly.

The top of the receiver is drilled and tapped for Weaver-style scope mounts (factory supplied) and a nifty magnesium cantilever scope mount can be added for $59. This dedicates the scope to a particular barrel so it will maintain its zero between swaps. The cantilever mount is also secured to a corresponding receiver mount by one screw, so the scope doesn’t float over the action. Use of the supplied action torque wrench on this screw, as well as the action screws, ensures return to zero.
During initial testing, the scope-barrel combo stayed in reasonable zero when switched out. A hunter would want to re-zero in camp (always a good idea) and this would entail moving the point of aim no more than an inch or less. I took apart and reassembled the .223 and .30-06 multiple times during the test. Both went right back very close to zero.Story By: Jeff John